1. Field of the Invention
The present invention relates generally to an ink-jet printing apparatus and a printing method. More particularly, the invention relates to an ink-jet printing apparatus and a printing method performing printing of characters, images and the like on a printing medium, such as a printing paper, an OHP film and the like using an ink and a liquid which makes a coloring material in the ink insoluble (hereinafter also referred to as a treatment liquid).
2. Description of the Related Art
A treatment liquid of this kind reacts with a coloring material contained in an ink, such as a pigment, dye and the like and makes the coloring material insoluble. In ink-jet printing technology, in general, the treatment liquid is ejected to overlay the portion of the printing medium where the ink is ejected or in the vicinity thereof, for admixing the ink and the treatment liquid to cause a reaction. Then, as a result of the reaction, the coloring material of the ink is fixed on the surface of the printing medium or penetrating into the printing medium for achieving water resistance of the printing product.
It has also been known that action for making the coloring material in the ink insoluble also serves for limiting penetration of the pigment or dye in a surface layer of the printing medium, to result in improvement of an optical density of the printing medium (hereinafter occasionally simply referred to as xe2x80x9cOD valuexe2x80x9d).
However, in the conventional ink-jet printing technology using the foregoing treatment liquid, it has been newly recognized by the inventors that there have been respective problems with the coloring materials to be employed in the ink for improving printing quality.
When a dye is used as the coloring material, a first problem that has been encountered is that a sufficiently high OD value cannot be obtained even when the dye and the treatment liquid react. This is because that the dye per se cannot develop a relatively low OD value as used for printing. Therefore, even if the treatment liquid and the dye are reacted to fix most of the dye in the surface layer of the printing medium as above-mentioned, the OD value is as high as the case where pigment is used as the coloring material.
The second problem the inventors have encountered with the dye is a phenomenon called xe2x80x9coverflowxe2x80x9d or xe2x80x9csweepxe2x80x9d, blurring an edge portion of a printed image.
FIGS. 1A to 1D are illustrations for explaining this phenomenon. As shown in FIG. 1A, when an ink Id using a dye as a color agent, is deposited on the lower penetrative printing medium P, such as a plane paper, by ejection of the ink through a printing head as an ejecting portion, a part of the ink penetrates into the printing medium and the remaining part of the ink is present in a liquid state on the surface of the printing medium P. Then, as shown in FIG. 1B, in the similar manner, a treatment liquid S is deposited over the ink Id to cause a reaction in the boundary between the treatment liquid S and the ink Id, by ejection through the printing head. As shown in FIG. 1C, a part of a reaction product flows out to the circumference of the ink Id and flows into the lower side of the ink Id. Then, a reaction between the dye in the ink Id and the treatment liquid S gradually progresses. Finally, an ink dot consisting of the reaction product of the dye and the treatment liquid is formed as shown in FIG. 1D The ink dot thus formed has a contour portion where the ink flows over a contour of the dot.
According to a prediction by the inventor, the foregoing phenomenon is caused by the flow of a gel from a high viscous reaction product in the ink and the treatment liquid for a relatively low reaction speed between the dye and the treatment liquid.
Flowing out of the ink in the ink dot shown in FIG. 1D due to such phenomenon makes a contour blur at the edge portion of an image, and appears as a so-called xe2x80x9coverflowxe2x80x9d to cause degradation of the printing quality. Fluidizing of the foregoing reaction product also causes xe2x80x9csweepingxe2x80x9d of the reaction product in the direction of the relative speed between the fed printing medium and the printing head for the treatment liquid. For this reason also, it has been predicted that the edge portion of the printed image becomes blurry.
The second problem concerning the dye set forth above may not occur where only dye ink is used and the treatment liquid is not used in printing. Accordingly, where printing is performed using the dye ink and the treatment liquid which makes the dye ink insoluble, this particular technical problem is encountered.
Moreover, even if printing is performed using an ink including a pigment as the coloring material and the treatment liquid therefor, a particular problem caused by the reaction between the ink and the treatment liquid will be explained hereinafter.
The pigment ink per se exhibits a relatively high OD value as used for printing. By reaction with the treatment liquid, owing to the effect of the treatment liquid set forth above, the OD value of the pigment ink can be improved. In comparison with the foregoing dye, the pigment has a high reaction speed with the treatment liquid.
However, as the first program in the case where pigment is used, the inventors have found a problem they call xe2x80x9ccrackxe2x80x9d. Namely, when reaction of the pigment ink and the treatment liquid is caused especially on the film-like printing medium for an OHP, since the reaction speed of the pigment with the treatment liquid is high as set forth above, most of the pigment coagulates on the surface before penetration into the printing medium. Furthermore, owing to the property of the pigment, the pigment may coagulate strongly. Therefore, after a solvent in the ink once penetrates into the printing medium and is fixed therein, the coagulated reaction product set forth above will become relatively large individual blocks due to the coagulation force to form gaps not filled in by the reaction product between these individual blocks. This phenomenon is perceived as a xe2x80x9ccrackxe2x80x9d upon observing the recording medium visually to degrade the quality of the printed image. When the foregoing reaction product is not filled in, the surface of the printing medium is exposed, to lower the OD value of the overall printed image.
Pigment ink includes an ink using a dispersant, such as a resin, a surface-active agent and the like, in order to stabilize dispersion of the pigment in the ink solvent (hereinafter occasionally referred to as dispersant-containing pigment ink), and an ink using a self-dispersion type pigment and containing no dispersant (hereinafter occasionally referred to as no dispersant containing pigment ink). The second problem concerning pigment ink is cause in the case where the latter no dispersant containing pigment ink and the treatment liquid are used.
The inventor has observed the phenomenon called xe2x80x9csoaking outxe2x80x9d or xe2x80x9cblurxe2x80x9d in a dot formed on the printing medium using the no dispersant containing pigment ink and the treatment liquid. FIGS. 2A to 2C are illustrations for predictively explaining this phenomenon.
After the application of the no dispersant containing pigment ink Ip on the printing medium P such as plain paper (see FIG. 2A), the treatment liquid is applied in an overlaying manner (see FIG. 2B). Then, production of reaction product is initiated, at first, from the reaction between the ink and the treatment liquid. Then, according to progress of this reaction, radial xe2x80x9csoaking outxe2x80x9d is caused from a substantially circular dot of the reaction product to xe2x80x9cblurxe2x80x9d the entire circumference of the dot (see FIG. 2C). Such xe2x80x9csoaking outxe2x80x9d or xe2x80x9cblurxe2x80x9d appears similar to known feathering. Accordingly, the printing quality is lowered.
The foregoing xe2x80x9csoaking outxe2x80x9d or xe2x80x9cblurxe2x80x9d is inferred as the following phenomenon chemically or in micro view. The no dispersant containing pigment ink has a relatively high reaction speed in reaction-with the treatment liquid. Therefore, the dispersed pigment instantly causes dispersion breakage to generate clustering of the reaction product. In conjunction therewith, a particulate reaction product is also generated. Then, the particulate reaction product flows out with penetration of the treatment liquid into the printing medium to result in the foregoing xe2x80x9csoaking outxe2x80x9d phenomenon.
As set forth above, in either case of performing printing using the dye ink and the treatment liquid and performing printing using the pigment ink and the treatment ink, there have been problems newly recognized by the inventors, in improving the printing quality, to be solved.
Associated with the respective foregoing problems, the applicant of the present invention has proposed the use of an ink and treatment liquid using dye ink and pigment ink containing dispersant (Japanese Patent Application Laid-open No. 8-267903). However, the invention disclosed in the above-identified patent application is different from the present invention.
The present invention has been worked out for solving the technical problems set forth above. It is therefore an object of the present invention to provide an ink-jet printing apparatus and a printing method that can solve or improve respective technical problems caused upon printing by using a dye ink or a pigment ink and a treatment liquid thereof to enable high quality printing.
Another object of the present invention is to provide an ink-jet printing apparatus and a printing method which can speed up a printing speed upon performing printing using the ink and the treatment liquid.
In a first aspect of the present invention, there is provided an ink-jet printing apparatus, in which after application of an ink containing a coloring material onto a printing medium, a treatment liquid making the coloring material of the ink insoluble is applied, the ink being a mixed ink, in which a self dispersion type pigment and a dye are mixed, comprising:
application means for separately applying the mixed ink and the treatment liquid onto the printing medium, for mixing the mixed ink and the treatment liquid in a liquid state on the printing medium.
According to a second aspect of the present invention, there is provided an ink-jet printing apparatus, in which after the application of an ink containing a coloring material onto a printing medium, a treatment liquid making the coloring material of the ink insoluble is applied, the ink being a mixed ink, in which a self dispersion type pigment and a dye are mixed, comprising:
application means for separately applying the mixed ink and the treatment liquid onto the printing medium, for mixing the mixed ink and the treatment liquid in a liquid state on the printing medium, and for mixture of the mixed ink and the treatment liquid, where a mixed ink, in which the self dispersion type pigment and the dye are mixed, is further applied on the printing medium in a liquid state.
In a third aspect of the present invention, there is provided an ink-jet printing apparatus employing an ink ejecting portion ejecting an ink and a treatment liquid ejecting portion ejecting a treatment liquid making an ink ejected from the ink ejecting portion insoluble and performing printing by ejecting the treatment liquid after ejection of the ink toward a printing medium, the ink ejecting portion being constituted of at least one mixed ink ejecting portion for ejecting a mixed ink, in which a self dispersion type pigment and dye are mixed, comprising:
ejecting portion arranging means for arranging the mixed ink ejecting portion and the treatment liquid ejecting portion in a predetermined positional relationship; and
control means for relatively moving respective ejecting portions arranged in the arranging means and the printing medium, ejecting the mixed ink and the treatment liquid from respective ejecting portions and mixing the mixed ink and the treatment liquid on the printing medium.
In a fourth aspect of the present invention, there is provided a printing method performing printing by applying a mixed ink, in which a self dispersion type pigment and a dye are mixed, onto a printing medium, and thereafter applying a treatment liquid making the self dispersion type pigment and the dye in the mixed ink insoluble, comprising:
a step of mixing at least the mixed ink and the treatment liquid by applying the mixed ink and the treatment liquid onto the printing medium.
In a fifth aspect of the present invention, there is provided a printing method performing printing by applying an ink containing a coloring material, and thereafter applying a treatment liquid making the coloring material in the ink insoluble, and the ink being a mixed ink, in which a self dispersion type pigment and a dye are mixed, comprising:
a step of separately applying the mixed ink and the treatment liquid onto the printing medium, mixing the mixed ink and the treatment liquid on the printing medium in liquid state, and, for a mixture of the mixed ink and the treatment liquid, a mixed ink, in which the self dispersion type pigment and dye are mixed, is mixed on the printing medium in a liquid state.
According to the present invention, since the mixed ink and the treatment liquid are mixed on the printing medium, xe2x80x9ccrackxe2x80x9d or xe2x80x9csoaking outxe2x80x9d, which could be caused upon printing by using only the pigment ink and the treatment liquid, can be suppressed by the presence of the dye simultaneously mixed. Conversely, lowering of the OD value or xe2x80x9coverflowxe2x80x9d, which could be caused upon printing by using only the dye ink and the treatment liquid, can be compensated for, or suppressed by the presence of the simultaneously mixed pigment.
In the present invention, the treatment liquid is effective if the penetration speed is higher than or equal to 5.0 (ml/m2xc2x7msec1/2) in Ka value by the Bristow method. Thus, in addition to the effect in the case where printing is performed by using the mixed ink and the treatment liquid, since the treatment liquid has a relatively high penetration ability, the reaction product of the pigment or the like and the treatment liquid may also have high penetration ability to achieve high penetration speed as a whole.
In a practical aspect of the present invention, the ink using the dye and the pigment with no dispersant as coloring materials (hereinafter referred to as mixed ink) is applied to the printing medium to form a dot of the reaction product by applying the treatment liquid.
FIGS. 3A to 3C are illustrations for explaining dot formation. As shown in FIG. 3A, at first, the mixed ink Im is applied to the printing medium. Then, as shown in FIG. 3B, the treatment liquid is applied overlaying the mixed ink Im. Therefore, the reaction product generated by reaction of the mixed ink Im and the treatment liquid S is fixed on the surface and inside of the printing medium P to form the dot.
According to one practical aspect, since the ink containing the dye and the pigment without dispersant is used for printing, lowering of the OD value caused by the dye ink can be compensated for by the pigment ink to enhance the OD value. Also, most of the reaction product of the ink as mixed with the treatment liquid may stay in an upper layer of the printing medium to contribute to an increase of the OD value.
When ink having low penetration speed is used as the mixed ink, even if the interval following the application of the treatment liquid provides a relatively long period for penetration, the amount of the coloring material staying in the surface layer of the printing medium can be made large to further improve the OD value. In other words, even if ink having a low penetration speed is used, i.e., the ink in which dye and pigment having no dispersants are mixed, the problem to be caused in using the dye ink and the pigment ink alone can be solved or reduced. By using ink having an even lower penetration speed, increasing of the OD value can be expected. Furthermore, the normal effect of using ink having a low penetration speed, i.e., so-called feathering, can be suppressed.
Next, the maximum effect of the invention, in which the treatment liquid is applied after application of the mixed ink on the printing medium, is to solve the problem of xe2x80x9coverflowxe2x80x9d or xe2x80x9csweepxe2x80x9d caused by the dye ink and to solve or reduce the problem of xe2x80x9csoaking outxe2x80x9d or xe2x80x9cblurxe2x80x9d caused by the pigment ink, simultaneously.
According to the inventors, the principle for achieving these effects can be explained as follow. After the application of the mixed ink onto the printing medium, the treatment liquid is applied. Then, the dye and the treatment liquid react to form a gel-form, high viscous substance. The pigment having no dispersant causes breakage of dispersion by reaction with the treatment liquid. It is understood that a fine particle of the pigment generated by dispersion breakage is taken into the high viscous substance of the dye reaction product to restrict xe2x80x9csoaking outxe2x80x9d or xe2x80x9cblurxe2x80x9d that could be caused by flowing out of the pigment particle. The high viscous substance taking in the pigment particles has a not so high flowability in comparison with the reaction product of the dye alone and the treatment liquid. Accordingly, the occurrence of xe2x80x9coverflowxe2x80x9d or xe2x80x9csweepxe2x80x9d can be suppressed simultaneously. Where the treatment liquid is applied to the mixture of the dye and the pigment having no dispersant, the fine particle of the pigment generated by dispersion breakage is taken in the gel form reaction product so as not to deeply penetrate into the printing medium to bury the gap between the fibers of the printing medium in the surface layer thereof. Then, the gel-form dye reaction product fills the gap between absorbed particles and the unevenness of the fiber on the surface of the printing medium. Therefore, irregular reflection of the light can be prevented to achieve an OD value higher than that achieved when the pigment and the treatment liquid are used.
According to one practical aspect of the invention, as diagrammatically shown in FIG. 3C, the phenomena that tend to degrade the printing quality, such as xe2x80x9cblurxe2x80x9d, xe2x80x9coverflowxe2x80x9d or the like, can be prevented. Furthermore, increasing of the OD value can be achieved.
The phenomena of xe2x80x9cblurxe2x80x9d or xe2x80x9coverflowxe2x80x9d tend to be caused by reaction of the pigment ink or the dye ink with the treatment liquid before penetration into the printing medium. Therefore, in order to suppress the occurrence of these phenomena, it becomes necessary to apply the treatment liquid after waiting for penetration of the dye ink or the like, which interferes with speeding up of the printing speed. However, since xe2x80x9cblurxe2x80x9d or the like can be suppressed by the mixed ink per se, which is a mixture of the dye and the pigment ink having no dispersant, it becomes unnecessary to set a waiting interval to await penetration of the dye ink before applying the treatment liquid. Accordingly, speeding up of the printing speed will not be interfered with. In other words, the OD value can be further improved by using the mixed ink of a practical aspect of the present invention having a relatively low penetration ability so that the coloring material, such as the pigment or the like, may stay in the surface layer of the printing medium for a long period.
In addition, in the inkjet printing apparatus employing the full-multi type head, the interval from the application of the mixed ink to the application of the treatment liquid can be shortened to speed up, the printing speed for the first one printing medium, known as the first print. On the other hand, since the foregoing interval can be shortened, down-sizing of the apparatus and lowering of cost can be achieved.
The order of application of the mixed ink and the treatment liquid onto the printing medium according to a practical aspect of the present invention is that the treatment liquid is applied after application of the mixed ink on the printing medium, as set forth above to attain the foregoing effect.
It is also within the scope of the invention to use the foregoing order of application in a serial-type head that scans the same region a plurality of times with an interval for paper feeding.
While the invention calls for applying the mixed ink in advance of applying the treatment liquid, the number of droplets of the mixed ink to be applied is not limited to one droplet as set forth above.
For example, it may be possible to apply two droplets of the mixed ink in advance of application of the treatment liquid. In this case, preferably, among these two droplets, the mixed ink applied at an earlier timing contains a greater proportion of dye than the pigment having no dispersant, and the mixed ink applied at the later timing contains a greater proportion of pigment having no dispersant than the dye. Therefore, upon the reaction with the treatment liquid applied later, a greater proportion of pigment may react with the treatment liquid to further suppress flow out of the reaction product of the dye and the treatment liquid. As another practical aspect of the invention that can achieve the equivalent effect, the number of the mixed ink droplets to be applied in advance of application of the treatment liquid is set to three and the proportions of the pigment having no dispersant are preferably increased in the mixed ink to be applied at a later timing.
When a plurality of mixed ink droplets are applied, the total amount of the applied ink is set to be substantially equal to the case where one droplet is applied. In other words, according to a practical aspect of the present invention, when the mixed ink is applied a plurality of times, even if the amount of the ink in each applied droplet is reduced, the foregoing effect can be attained.
Differences in the timings of the application of the mixed ink and the treatment liquid may be encompassed within the scope of the present invention as long a respective effect of the practical aspect of the present invention can be achieved, similarly to the order of application set forth above.
More specifically, different modes of reaction between the mixed ink and the treatment liquid occur, depending upon the timing from the application of the mixed ink to the application of the treatment liquid. For example, when the time is short, mixing of the mixed ink and the treatment liquid becomes insufficient. In the circumferential portion of the dot formed by overlaying the mixed ink and the treatment liquid, namely the edge portion, mixing of the pigment or the like and the treatment liquid can be done sufficiently to achieve the advantageous effect of the present invention, particularly in suppression of xe2x80x9cblurxe2x80x9d or xe2x80x9coverflowxe2x80x9d.
Therefore, in this disclosure, xe2x80x9cmixxe2x80x9d and xe2x80x9cmixingxe2x80x9d of the mixed ink and the treatment liquid refers not only to complete mixing but also to partial mixing at the edge portion, and so on. Furthermore, xe2x80x9cmixxe2x80x9d and xe2x80x9cmixingxe2x80x9d of the mixed ink and treatment liquid also refers to mixing after penetration into the printing medium. Modes of all of these mixing operations will be defined as xe2x80x9cmixing in a liquid statexe2x80x9d.
The color (kind), density, and number of the ink droplets applied according to the present invention can be combined arbitrarily as long as the foregoing order of application is maintained. For example, as the kind of ink, black (Bk), yellow (Y), magenta (M) and cyan (C) inks are used generally. Concerning respective colors, high and low density inks may also be used. Further, with taking at least one of yellow ink, magenta ink and cyan ink as mixed ink according to the present invention, and using the treatment liquid, the mixed ink and the treatment liquid are applied in sequential order.
Among such combinations, to which the present invention is applicable, the most preferred mode is for the mixed ink to comprise black ink. According to this combination, the advantageous, effect of the invention, such as increasing of the OD value, and suppressing of xe2x80x9cblurxe2x80x9d or xe2x80x9coverflowxe2x80x9d contributes to the printing quality of characters, such as letters or the like.
As a method of applying the mixed ink, and so on, to the printing medium, various methods, such as the application method or directly contacting the ink, or the like, to the printing medium, and so on, may be encompassed within the scope of the present invention. The most preferred mode is the ink-jet printing mode employing a printing head. In this case, the combination and arrangement of the printing head or heads as the ejecting portion is determined according to the combination of the application order and the kinds of ink and treatment liquid.
Particularly, by a construction, in which the heads for the mixed ink and the treatment liquid are arranged in a direction of relative movement of the printing head with respect to the printing medium, the foregoing sequential order of application becomes possible.
More specifically, either a so-called full-multi type printing head may be used, in which the ink ejection openings are arranged within a range corresponding to the entire width of the printing region in the printing medium, or a serial type printing head may be used, in which scanning occurs relative to the printing medium. Either case permits the application of the ink and the treatment liquid.
In the ink ejection system of the printing head, any known type, such as piezo type or the like, can be employed. The most preferred mode is to generate a bubble in the ink or the treatment liquid utilizing thermal energy to eject the ink or the treatment liquid by the pressure of the bubble.
Furthermore, by each printing head, a range where the mixed ink and the treatment liquid are ejected to overlay each other, is normally controlled per pixel for forming the printed image, or so on. The foregoing ink or the like are ejected at the same position in an overlaying manner. However, the application of the present invention is not limited to the foregoing construction. For example, the present invention encompasses a construction in which a part of a dot of the mixed ink and the treatment liquid are overlaid to achieve the predetermined effect of the invention or a construction, in which the treatment liquid is applied for data of respective pixels with thinning to cause a reaction between the treatment liquid and the pigment or the like flowing from an adjacent pixel by bleeding or the like.
Another practical aspect of the present invention will be explained.
This practical aspect is intended to achieve high speed fixing by employing a treatment liquid having a high penetration ability.
High speed fixing is a major factor in achieving speeding up of the printing speed, thereby improving the throughput. By increasing the driving frequency of the printing head or the transporting speed of the printing medium, direct improvement of the throughput becomes possible. However, when the ink or the like on the printing medium discharged after printing is not yet fixed, inconvenience can be caused in subsequent handling. Also, where the discharged printing media are stacked, non-fixed ink on one recording medium may cause a stain of other printing media.
Among various factors contributing to speeding up of the printing speed, are the discharge speed of the printing medium after completion of printing, which depends on the feeding speed of the printing medium and the scanning speed of the printing head. In a printing apparatus employing a full-multi type printing head, the feeding speed of the printing medium in the printing operation directly corresponds to the discharge speed. In a printing apparatus employing a serial type printing head, the scanning speed is directly associated with the discharge speed of the printing medium after the completion of printing. Then, the feeding speed of the printing medium and so on is correlated with the ink ejection period for a pixel via a solution of printing problems, namely via the dot density. Therefore, in a printer performing printing of one pixel by the ink ejected from a plurality of printing head, when the resolution is considered to be fixed, the ejection period and the feeding speed, and so on, with respect to the pixel, is correlated.
In consideration of respective technical tasks relating to reaction of the dye ink and the pigment ink with the treatment liquid, it is preferred to make the period from ink ejection to ejection of the treatment liquid as long as possible. The reason is that, when the dye ink or the pigment ink reacts with the treatment liquid after penetration into the printing medium, the foregoing phenomena that diminish print quality will hardly occur. In other words, when printing is performed using a dye ink, a pigment ink and treatment liquid therefor, the foregoing long period from ink ejection to the ejection of the treatment liquid problem also interferes with speeding up of the printing speed. Particularly, when dye ink and pigment ink having a low penetration speed are used for achieving improvement of the OD value, the problem with interfering with the speeding up of printing becomes particularly significant.
According to one practical aspect of the invention, after the application of the mixed ink on the printing medium, by applying a treatment liquid having a high penetration speed, the advantageous effect set forth in the first practical aspect of the invention can be realized. Even if a mixed ink having a relatively low penetration speed is used, the penetration speed is increased by the associated high penetration speed treatment liquid. Namely, when the penetration speeds of the mixed ink and the treatment liquid with respect to the printing medium are v1 and v2 respectively, v1 less than v2 is satisfied. In FIG. 4, this phenomenon is explained.
FIG. 4 shows the case where the mixed ink Im and the treatment liquid S are applied to the printing medium P in sequential order. In this case, a reaction product starts to be generated between the treatment liquid S and the mixed ink Im contacting each other at a boundary therebetween. The penetration speed of the mixture between the treatment liquid S and the mixed ink becomes higher than that of the case where the mixed ink is used alone. Thus, as a whole, by speeding up of the penetration speed to be higher than that in the mixed ink alone, high speed fixing becomes possible.
By using a treatment liquid having a high penetration speed, particularly when a mixed ink having a low penetration speed is used, for improving the OD value or the like, relatively high speed fixing can be achieved.
A still further practical aspect of the present invention relates to the order of application of the mixed ink and the treatment liquid. Namely, according to the practical aspect, after application of the mixed ink, the treatment liquid is applied, and thereafter, the mixed ink is further applied.
This aspect of the invention is particularly effective in improving the OD value, the restriction of xe2x80x9coverflowxe2x80x9d, xe2x80x9cblurxe2x80x9d or feathering among the foregoing effects. Using a treatment liquid having a high penetration ability as the treatment liquid to be applied between applications of the mixed ink, a relatively high fixing ability can be obtained.
The foregoing function and effect of this practical aspect of the invention is achieved due to the reduced amount of fluidization caused in reaction between the initially applied mixed ink and the treatment liquid as a result of the relatively small amount of the mixed ink used. When the mixed ink is applied after the application of the treatment liquid, since the viscosity due to the reaction between the initially applied mixed ink and the treatment liquid increases to a certain extent and penetration of the ink and so on also progresses to a certain extent, flowability is lowered.
The ink to be applied after the application of the treatment liquid is preferred to be the mixed ink set forth above, but can be a self-dispersion type pigment ink or a dye ink
According to a sixth aspect of the present invention, there is provided an ink-jet printing apparatus applying a first ink containing a coloring material to a printing medium, applying a treatment liquid for making the coloring material in the first ink insoluble and applying a second ink containing a coloring material, wherein
the ink includes a pigment ink primarily containing a pigment as the coloring material and a dye ink primarily containing a dye as the coloring material, the apparatus comprising applying means for separately applying the pigment ink, the dye ink and the treatment liquid, and, on the printing medium, the pigment ink and the dye ink being mixed with the treatment liquid in a liquid state, respectively.
According to a seventh aspect of the present invention, there is provided an ink-jet printing apparatus applying one of a pigment ink containing a pigment as a primary coloring material and a dye ink containing a dye as a primary coloring material on a printing medium, thereafter applying a treatment liquid making the coloring material in the ink insoluble, and subsequently applying the other of the pigment ink and the dye ink onto the printing medium, comprising:
applying means for separately applying the pigment ink, the dye ink and the treatment liquid, and, on the printing medium, the pigment ink and the dye ink are mixed with the treatment liquid in a liquid state respectively.
According to an eighth aspect of the present invention, there is provided an ink-jet printing apparatus, having an ink ejecting portion ejecting an ink containing a coloring material, and a treatment liquid ejecting portion ejecting a treatment liquid making a coloring material in the ink insoluble, for performing printing by ejecting the treatment liquid after ejecting the ink toward a printing medium, the ink ejecting portion including a dye ejecting portion ejecting a dye ink primarily containing a dye as a coloring material and a pigment ejecting portion ejecting a pigment ink primarily containing a pigment as a coloring material, comprising:
ejecting portion arranging means for arranging the dye ink ejecting portion, the pigment ink ejecting portion and the treatment liquid ejecting portion in a predetermined positional relationship; and
control means for relatively moving the ejecting portions arranged by the arranging means and the printing medium, ejecting the pigment ink, the dye ink, and the treatment liquid from the ejecting portions, and mixing the pigment ink, the dye ink, and the treatment liquid on the printing medium in a liquid state.
According to a ninth aspect of the present invention, there is provided an printing method performing printing by applying an ink containing a coloring material, and thereafter applying a treatment liquid making the coloring material in the ink insoluble, the ink including a pigment ink containing a pigment as a primary coloring material and a dye ink containing a dye as a primary color agent, comprising:
a step of separately applying the pigment ink, the dye ink and the treatment liquid onto the printing medium, mixing the pigment ink, the dye ink and the treatment liquid on the printing medium in a liquid state, at least the pigment ink, the dye ink and the treatment liquid being mixed in liquid state.
In the present invention, since the pigment ink, the dye ink and the treatment liquid are mixed on the printing medium, xe2x80x9ccrackxe2x80x9d or xe2x80x9csoaking outxe2x80x9d which could be caused upon printing using the pigment ink and the treatment liquid, can be reduced by the simultaneously mixed dye ink. Conversely, lowering of the OD value or xe2x80x9coverflowxe2x80x9d which could be caused upon printing using only the dye and the treatment liquid can be compensated for or reduced by the simultaneously mixed pigment.
In the present invention, the treatment liquid is effective when the penetration speed is higher than or equal to 5.0 (ml/m2xc2x7sec1/2) in Ka value by the Bristow method. Upon printing with mixing the dye ink, the pigment ink, and the treatment liquid, in addition to the foregoing function, since the treatment liquid having a relatively high penetration ability is used, the reaction product of the pigment ink or the like and the treatment liquid also has a high penetration ability to speed up the penetration speed as a whole.
According to another practical aspect of the present invention, the dye ink and the pigment ink are mixed on the printing medium, and the treatment liquid is applied to the mixture of the dye ink and the pigment ink to form a dot by the reaction product.
FIGS. 5A to 5D are illustrations for explaining the formation of the dot. As shown in FIG. 5A, at first, the dye ink Id is applied to the printing medium. Then, as shown in FIG. 5B, the pigment ink Ip is applied overlaying the dye ink Id. Also, as shown in FIG. 5C, to the liquid, in which the dye ink Id and the pigment ink Ip are mixed, the treatment liquid S is applied. Therefore, the reaction product, generated by reaction of the mixture liquid of the inks and the treatment liquid S, is fixed on the surface and inside of the printing medium P to form the dot, as shown in FIG. 5D.
According to this practical aspect of the invention, at first, the dye ink and the pigment ink are the mixed on the printing medium, and the mixed ink is used for printing. Therefore, lowering of the OD value caused by printing by the dye ink can be compensated for the pigment to enhance the OD value. Furthermore, the reaction product of the treatment liquid and the mixed ink stays in the upper layer portion of the printing medium in a large proportion to increase the OD value.
When the dye ink and the pigment ink having a low penetration speed are used, if the period to application of the treatment liquid is long to provide a long period for penetration, a large proportion of the coloring material may stay in the surface layer of the printing medium to enhance the OD value. In other words, by the effect of using both the dye ink and the pigment ink explained later, even if the ink having a low penetration speed is used, the problems that could be caused when the dye ink and the pigment ink are used alone, can be solved or reduced. Therefore, the dye ink or the pigment ink having an even lower penetration speed can be used. Thus, further increasing of the OD value can be expected. Furthermore, as an effect of using of ink having a low penetration speed, per se, so-called feathering can be restricted.
Secondly, in addition to the effect of improvement of the OD value set forth above, as the effect of printing by mixing the dye ink and the pigment ink on the printing medium, the problem of xe2x80x9ccrackxe2x80x9d can be solved or reduced.
When the printing medium, such as plain paper or the like is used, the dye ink and the pigment ink are mixed on the printing medium, and subsequently, the treatment liquid is applied. The pigment may react with the treatment liquid to coagulate and to generate a block of the reaction product. In mutual gap between a plurality of blocks thus generated, the reaction product of the dye reacted with the treatment liquid is fluidized to penetrate therein for fill. Therefore, the occurrence of so-called xe2x80x9ccrackxe2x80x9d set forth above can be prevented and restricted.
As the third effect of the practical aspect of the invention, in which the dye ink and the pigment ink are mixed on the printing medium and the treatment liquid is applied to the mixed inks, the problem of xe2x80x9coverflowxe2x80x9d or xe2x80x9csweepxe2x80x9d that could be caused in printing by the dye ink and the problem of xe2x80x9csoaking outxe2x80x9d or xe2x80x9cblurxe2x80x9d that could be caused upon printing with the pigment ink containing no dispersant can be solved or reduced simultaneously.
According to the inventors, the principle achieving these effects can be explained as follow. After the application of the mixed ink onto the printing medium, the treatment liquid is applied. Then, the dye and the treatment liquid react to form a gel-form, high viscous substance. The pigment having no dispersant causes breakage of the dispersion by reaction with the treatment liquid. It is understood that the fine particles of the pigment generated by the dispersion breakage are taken into the high viscous substance of the dye reaction product to restrict xe2x80x9csoaking outxe2x80x9d or xe2x80x9cblurxe2x80x9d that could be caused by flowing out of the pigment particles. The high viscous substance absorbing the pigment particle has not too great a flowability in comparison with the reaction product of the dye alone and the treatment liquid. Accordingly, the occurrence of xe2x80x9coverflowxe2x80x9d or xe2x80x9csweepxe2x80x9d can be suppressed simultaneously. Where the treatment liquid is applied to the mixture of the dye and the pigment having no dispersant, the fine particles of the pigment generated by dispersion breakage are taken in the gel-form reaction product so as not to deeply penetrate into the printing medium to bury a gap between the fibers of the printing medium in the surface layer. Then, the gel-form dye reaction product fills in the gap between the absorbed particles and the unevenness of the fibers on the surface of the printing medium. Therefore, irregular reflection of the light can be prevented to achieve an OD value higher than that achieved when the pigment and the treatment liquid are used.
According to one practical aspect of the invention, as diagrammatically illustrated in FIG. 5D, in conjunction with the restriction of the occurrence of a phenomenon, such as xe2x80x9cblurxe2x80x9d or xe2x80x9coverflowxe2x80x9d, which could be a factor for degrading printing quality, the effect of increasing of the OD value and xe2x80x9ccrackxe2x80x9d can be achieved as set forth as the foregoing first and second effects.
The phenomenon of xe2x80x9cblurxe2x80x9d or xe2x80x9coverflowxe2x80x9d can be caused by reacting the pigment ink or the dye ink with the treatment liquid before penetration into the printing medium. Therefore, in order to suppress the occurrence of these phenomena, it becomes necessary to apply the treatment liquid after waiting for penetration of the dye ink or the like, which interferes with the speeding up of the printing speed. However, according to this practical aspect of the invention, since xe2x80x9cblurxe2x80x9d or the like can be suppressed by the mixed ink per se, which is a mixture of the dye and the pigment ink having no dispersant, it becomes unnecessary to set a waiting interval for penetration of the dye ink or the like into the printing medium before applying the treatment liquid. Accordingly, speeding up of the printing speed will not be interfered with. In other words, the OD value can be further improved by using the mixed ink according to a practical aspect of the invention having a relatively low penetration ability so that the coloring material, such as the pigment or the like may stay in the surface layer of the printing medium for a long period.
In addition, in the ink-jet printing apparatus employing a full-multi type head, the interval from the application of the mixed ink to the application of the treatment liquid can be shorted to speed up the printing speed for the first one printing medium, known as the first print. Since the foregoing interval can be shortened, down-sizing of the apparatus and lowering of cost can be achieved.
The order of application of the mixed ink and the treatment liquid onto the printing medium according to a practical aspect of the invention is that the treatment liquid is applied after application of the mixed ink on the printing medium, as set forth above to attain the foregoing effect.
According to a study made by the inventors, among the foregoing orders of application, it has been appreciated that the sequential order of the pigment ink, the dye ink, and the treatment liquid or the sequential order of the dye ink, the pigment ink, and the treatment liquid are preferred. This is because the advantageous effect of mixing according to the present invention is most significant when the dye ink and the pigment ink are mixed to a certain extent and thereafter a reaction is caused with the treatment liquid.
Among two sequential orders set forth above, when the pigment ink, the dye ink and the treatment liquid are applied in this order, in addition of the advantageous effect set forth above, the effect of restricting so-called strike through can be achieved. Namely, deeper penetration of the coloring material of the dye or the like into the printing medium, called a strike through because the dot formed by this coloring material can be remarkably observed from the back side of the printing medium, can be caused. However, in the sequential order of application set forth above, substantially no strike through can be observed. The inventors suppose that for this reason for this is that since the pigment applied at an earlier timing has relatively large particles in the reaction product with the treatment liquid, the reaction product may be clogged in the gap between the fibers or the like of the printing medium, making it impossible to penetrate any further.
In the sequential order of application of the dye ink, the pigment ink and the treatment liquid, xe2x80x9coverflowxe2x80x9d or the like, which could be caused using the dye ink and the treatment liquid, is hardly caused.
Differences in the timings of the application of the mixed ink according to the invention and the treatment liquid may be encompassed within the scope of the present invention as long as the advantageous effect of the practical aspect of the invention can be achieved, similarly to the order of application set forth above.
For example, the timing difference of application of the pigment ink and the dye ink can be zero. Namely, the pigment ink and the dye ink may be applied to the printing medium simultaneously. Also, the interval from the application of the pigment ink or the like to the application of the treatment liquid is desired to include a time for mixing the pigment ink and the dye ink in order to obtain the advantageous effect of the practical aspect of the invention set forth above. However, even in a period shorter than the foregoing interval, in the peripheral portion of the dot formed by overlaying the pigment ink and the like, namely the edge portion, sufficient mixing of the pigment and the like can be caused to achieve the advantageous effects of the practical aspect of the invention. Particularly, at least the effect of suppression of xe2x80x9cblurxe2x80x9d or xe2x80x9coverflowxe2x80x9d can be achieved.
The color (kind), density and amount of the ink applied according to the practical aspect of the invention can be combined arbitrarily as long as the foregoing order of application is maintained. For example, as the kind of ink, black (Bk), yellow (Y), magenta (M) and cyan (C) inks are used generally. Concerning respective colors, high and low density inks may also be used. Further, with taking at least one of yellow ink, magenta ink and cyan ink as mixed ink according to the practical aspect of the invention, and using the treatment liquid, the mixed ink and the treatment liquid are applied in sequential order.
Among such combinations, to which the present invention is applicable, the most preferred mode is for the mixed ink to comprise black ink. With this mode, the advantageous effect of the invention, such as increasing of the OD value, and suppressing of xe2x80x9cblurxe2x80x9d or xe2x80x9coverflowxe2x80x9d contributes to the printing quality of characters, such as letters or the like.
In the foregoing explanation, the pigment ink and the dye ink have been explained as those containing only pigment and only dye as coloring material components, respectively, and the various effects set forth above can be achieved not only by the inks set forth above, but also by a pigment ink partly containing the dye or the dye ink partly containing pigment. This the true even for the following explanation. Therefore, in this disclosure, as the coloring material, ink containing the pigment only or ink containing the pigment partly containing dye are defined as xe2x80x9cpigment ink containing the pigment as primary coloring materialxe2x80x9d. Also, ink containing the dye only or ink containing the dye partly containing the pigment are defined as xe2x80x9cdye ink containing the dye as primary coloring materialxe2x80x9d.
As a method of applying these mixed inks and so on, to the printing medium, various methods, such as the application method or directly contacting the ink, or the like, to the printing medium, and so on, may be encompassed within the scope of the present invention. The most preferred type is the ink-jet printing type employing a printing head. Then, in this case, the combination and arrangement of the printing head or heads as the ejecting portion, is determined according to the combination of the application order and the kinds of ink and treatment liquid.
Particularly, by a construction, in which the heads for the mixed ink and the treatment liquid are aranged in a direction of relative movement of the printing head with respect to the printing medium, the foregoing sequential order of application becomes possible.
Furthermore, by each printing head, a range where the pigment ink, the dye ink and the treatment liquid are ejected to overlay, is normally controlled per pixel for forming the printed image, or so on. The foregoing ink or the like, are ejected at the same position in an overlaying manner. However, the application of the present invention is not limited to the foregoing construction. For example, the present invention encompasses a construction in which a part of a dot of the pigment ink, the dye ink and the treatment liquid are overlaid to achieve the predetermined effect of the practical aspect of the invention or a construction, in which the treatment liquid is applied for data of respective pixels with thinning to cause a reaction between the treatment liquid and the pigment, or the like, flowing from an adjacent pixel by bleeding or the like.
According to another practical aspect of the invention, by applying a treatment liquid having a high penetration speed after the application of the dye ink and the pigment ink onto the printing medium, the effect explained in the fourth practical aspect of the invention can be achieved. Also, even if dye ink and pigment ink having a relatively low penetration speed are used, the penetration speed can be made higher. According to this aspect of the invention, the penetration speeds of the pigment ink, the dye ink and the treatment liquid relative to the printing medium are v1 less than v3 and v2 less than v3 assuming that the penetration speed of the pigment ink is v1, the penetration speed of the dye ink is v2 and the penetration speed of the treatment liquid is v3.
FIG. 6 shows the case where the pigment ink Ip the dye ink Id and the treatment liquid S are applied on the printing medium P in the sequential order, and shows a condition where the treatment liquid S is applied at a timing where the pigment ink Ip and the dye ink Id are not mixed sufficiently. In this case, the reaction product is generated at the boundary where the treatment liquid S and the dye ink Id contact. At first, since the penetration speed of the treatment liquid S is high, the reaction product may penetrate at a higher speed than that when the dye ink is used alone. Since the reaction between the dye and the treatment liquid per se is relatively small, the treatment liquid S further penetrates during reaction to also react with the pigment ink Ip to make the penetration speed of the reaction product higher. Thus, as a whole, the penetration speed can be higher than the penetration speed in the case where the pigment ink and the dye ink are used alone to permit a high speed fixing.
According to this practical aspect of the invention, by using a treatment liquid having a high penetration speed, even if a pigment ink and dye ink having a low penetration speed are used for improvement of the OD value and so on, fixing at a relatively high speed becomes possible.
Another practical aspect of the present invention concerns the order of application of one of the pigment ink, the dye ink and the treatment liquid. Namely, after the application of the dye ink or the pigment ink, the treatment liquid is applied, and subsequently, the other of the pigment ink and the dye ink is applied. More particularly, the application of elements is performed in the order of the dye ink, the treatment liquid and then the pigment ink, or in the order of the pigment ink, the treatment ink and then the dye ink.
According to this aspect of the invention, in comparison with the aspect in which the treatment liquid is applied after the application of both of the pigment ink and the dye ink, the flow ability of the reaction product generated by the reaction between the ink and the treatment liquid is lowered, which is advantageous in the prevention of xe2x80x9coverflowxe2x80x9d and xe2x80x9csweepxe2x80x9d.
According to the present invention, since the pigment ink, the dye ink and the treatment liquid are mixed on the printing medium, xe2x80x9ccrackxe2x80x9d or xe2x80x9csoaking outxe2x80x9d, which could be caused when printing is performed only with the pigment ink and the treatment liquid, can be reduced by the presence of the simultaneously mixed dye ink. Conversely, lowering of the OD value or xe2x80x9coverflowxe2x80x9d, which could be caused when printing is performed only by the dye and the treatment liquid, can be compensated for by the presence of the simultaneously mixed pigment ink and thus can be reduced.
As a result, high quality printing can be performed with a high OD value and by avoiding phenomena such as xe2x80x9ccrackxe2x80x9d, xe2x80x9csoaking outxe2x80x9d, xe2x80x9coverflowxe2x80x9d, and so on.
In addition to the effect to be achieved by printing with mixing the pigment ink and the treatment liquid, since the treatment liquid having a relatively high penetration ability is used, the reaction product of the pigment ink and the treatment liquid may have a high penetration ability to make the penetration speed high as a whole.
As a result, the fixing speed can be made higher to enable high speed printing.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of the embodiments thereof taken in conjunction with the accompanying drawings.